Winners and losers in the cyclone seasons

A total of 7 typhoons developed across the West Pacific during October (Fitow, Danas, Phailin, Nari, Wipha, Francisco, Lekima and Krosa) [Nasa]

Super Typhoon Haiyan, the most powerful storm to make landfall on record, has caused catastrophic damage in the Philippines.

It comes after the most active October on record in the region. A total of 7 typhoons developed across the West Pacific during October (Fitow, Danas, Phailin, Nari, Wipha, Francisco, Lekima and Krosa). This beat the previous record of 6 back in 1989.

The formation of Haiyan brings the number of named storms in the Western Pacific this year to 28, making it the busiest season since 2004, when 32 named storms were reported.

On the other side of the Pacific, storm activity has followed a more typical pattern. The formation of 18 named storms and 7 hurricanes was close to the Joint Typhoon Warning Center‘s pre-season predictions, and the 1981-2010 average of 15 named storms and 8 hurricanes.

Curiously, while in a typical season we would expect four major hurricanes (Category 3 or above on the Saffir-Simpson scale, with 5 being the highest), this year there has been just one, Hurricane Manuel.

Manuel turned out to be one of the worst in Mexico’s history. When it made landfall near Manzanillo in mid-September, it brought devastating flooding, causing $4 billion worth of damage and killing almost 170 people, one of the ten deadiest tropical cyclones ever recorded in the Eastern Pacific.

Meanwhile, in the Atlantic basin, the hurricane season has been one of the quietest on record, and early November has shown no sign of any significant upsurge in activity.

That is not to say that a major storm will not occur. In fact, there is some statistical evidence to suggest that late season storms are increasing in frequency. In 11 of the last 18 seasons there has been at least one or more named storms. Of these, Hurricane Lenny in 1999 was both the strongest and deadiest. It reached Category 4 and killed 17 people.

Currently, there are mixed signs for potential storm development. Sea surface temperatures are above the required 26C threshold. Winds through the atmosphere are also showing relatively little change with height, which aids storm development.

The Madden Julian Oscillation, a band of thunderstorm activity which moves around the equator every 30 to 60 days is also in a favourable position, but only for the next two weeks.

Against this, there is a lot of dry, subsiding air across the Atlantic which will hinder cloud development. So if there is to be any late activity in the Atlantic it will have to happen soon, or the Atlantic’s tropical cyclone season will be left far behind by its Pacific counterpart.